Automotive vehicles are becoming commonly equipped with antennas that receive and process signals other than traditional AM/FM signals, such as, for example, satellite signals. In particular, antennas relating to satellite digital audio radio services (SDARS), which is broadcast on the 2320-2345 MHz frequency band, is becoming widely available in vehicles as an originally-installed component by an original equipment manufacturer (OEM), or, alternatively, as an after-market component that is installed after the vehicle has been manufactured by the OEM. SDARS offer a digital radio service covering a large geographic area, such as North America. Satellite-based digital audio radio services generally employ either geo-stationary orbit satellites or highly elliptical orbit satellites that receive up-linked programming, which, in turn, is re-broadcast directly to digital radios in vehicles on the ground that subscribe to the service.
SDARS antennas, such as, for example, patch antennas, presently track two satellites at a time. Thus, the location of the SDARS patch antennas on a vehicle is critical for obtaining proper reception. As a result, SDARS patch antennas may be mounted on the vehicle exterior, usually on the roof. Some SDARS antennas have been located at locations other than the vehicle roof in a “hidden antenna” application; however, reception performance of the antenna may be compromised if the antenna is moved away from the roof. To achieve higher gains for improving the antenna performance, antennas have been positioned at different locations on the vehicle with the output of each antenna summed in a phase array summation implementation. Another methodology to improve antenna performance includes two or more antennas positioned at different locations on a vehicle in a switched diversity application where signal reception is switched amongst antenna elements if the receiving antenna element loses the signal.
Although adequate for most situations, the phase array summation implementation introduces design and installation complexities. Even further, the switched diversity implementation does not achieve a higher gain of the received satellite signal. A need therefore exists for an improved antenna system that provides reception of SDARS signals while achieving higher gains and maintaining vehicle aesthetics.